Aerosols, gel products, solutions, powders, synthetic resin products and the like are known in the prior art as the forms of aromatics, deodorants, antimicrobial agents and the like, and a number of attempts have been made particularly to adhere or include perfumes and the like aromatic substances to or in synthetic resins. In general, since there is no compatibility between aromatic substances and synthetic resins, an aromatic substance included in a resin exudes therefrom to the resin surface and rapidly lose its effects or the aromatic substance is sealed in the resin and does not diffuse to the surface, so that the effects expected as an aromatic cannot fully be exerted. For example, chain hydrocarbon based thermoplastic resins such as polyethylene and polypropylene are inferior in gas permeability and styrene based and polyvinyl acetate based resins have too much gas permeability, so that all of these resins are not suitable as base materials for aromatic substances.
With the aim of resolving these disadvantages of synthetic resin products, various methods have been proposed, such as a method in which an aromatic substance is supported on a hydrophilic polymer such as an hydrophilic acrylate or hydrophilic methacrylate (JP-B-49-4946: the term "JP-B" as used herein means an "examined Japanese patent publication"), a method in which a chlorine compound of polyethylene or a polyethylene copolymer is used (JP-B-50-29015), a method in which a low molecular weight polyolefin resin is mixed with a perfume and melted, and the resulting pellets are mixed with a high molecular weight polyolefin resin (JP-B-54-37974) and a method in which a perfume is entrapped in a copolymer of ethylene with vinyl acetate or various acrylic esters (JP-B-53-98352) or absorbed therein by impregnation (JP-B-56-121560). Also proposed is a resin composition for aromatic material use in which a perfume evaporation controlling agent such as benzyl benzoate is included in an ethylene-vinyl acetate copolymer (JP-B-63-6099).
Though there are products already realized as aromatics and deodorants by including aromatic substances in these synthetic resins to be used as base materials, almost all of these synthetic resins described above have no biodegradability and are not easily be decomposed when left in the natural environment after their use, so that they become a cause of environmental pollution. In consequence, it is desirable to recover them after use and carry out their incineration or recycling, but such operations impose a large economical burden.
As a method for resolving such a problem, products which do not violate the natural environment have positively been proposed by the use of a synthetic resin as the base material which has so-called biodegradability that renders possible easy decomposition of the resin making use of microorganisms distributed in the natural world.
Recently, several aromatics, deodorants, antimicrobial agents and the like have been proposed in which synthetic resins having biodegradability are used as the base material. For example, a biodegradable expansion molding product comprised of wheat flour, starch and water (JP-A-5-320401: the term "JP-A" as used herein means an "unexamined published Japanese patent application"), a volatile drug-containing material comprised of porous cellulose (JP-A-6-65412), a perfume-containing foam comprised of pulp (JP-A-6-107838) and the like have been proposed, but all of these synthetic resins used as the base material lack in transparency and cannot yet be said practically useful in terms of their compatibility with aromatic substances and hardness, strength and the like of the resins.
In addition, an antimicrobial composition in which an antimicrobial perfume, hinokitiol, is included in a low molecular weight lactic acid-glycolic acid copolymer has also been proposed (JP-A-5-97619), but having disadvantages in that the molding forms are restricted due to the low molecular weight of the material to be used as the base, the material itself is very apt to be hydrolyzed and controlled release of hinokitiol cannot be effected without accelerating decomposition of the base material because hinokitiol does not permeate through the base material easily.